A continuously adjusting transmission basically consists of a starting unit, especially a torque converter, a forwards/backwards drive unit with a turning set, an intermediate shaft, a differential, hydraulic and electronic control devices as well as a variator.
In the current state of the art transmissions, the variator includes a primary side which is connected to the drive shaft and a secondary side, which respectively includes a pair of conic pulleys. One of the conic pulleys is statically placed in the axial direction, while the other is movably placed in the axial direction. A variator with a torque transferring clasping element is further provided which turns between the two conic pulley pairs. The used clasping element is usually a thrust linking band, a traction chain or a belt. The current transmission transfer is defined by the barrel radius of the clasping element which, in turn, is a function of the relative axial position of the conic pulleys on the primary and the secondary side.
Under the current state of the art, the relative axial position of the conic pulleys on the primary and the secondary sides would be hydraulically adjusted. Hydraulic pressure would hereby be required for the mobile conic pulleys, in such a way that the relative axial distance of the conic pulleys is a function of the adjusted pressure. For this purpose, the pressurized oil fed from a hydraulic pump must be conducted through a longitudinal borehole in the variator shaft, at least one radial borehole in the variator shaft and a radial borehole in the locating disc in the corresponding pressure chamber.
In the current state of the art, it is known that in order to implement the pressure supply in the variator disc in such a way that the shaft borehole and the locating disc must be exactly aligned between themselves when they find the shaft in the stop position, i.e., in a pressure less position. A duct is located in the locating disc in the axial and radial direction over the shaft borehole which ensures the oil conduction when the disc is moved away from the stop position. This means that the shaft borehole and the locating disc are not superimposed. The locating disc adjustment, therefore, will be typically ensured by taking away one tooth from the shaft profile of the variator shaft and a tooth gap is accordingly filled in the locating disc.
The need for removing a profile tooth from the variator shaft, as well as the required duct in the locating disc, will cause high manufacturing costs. Besides, the assembly process is very elaborate and, as it has already been explained, an oriented assembly is required.
A continuously adjustable clasping transmission is known from the DE 102 22 001 A1 model in which the axially movable conic pulleys of the drive shaft, during the transmission pressureless condition, is loaded through a spring array with an axial force, which increases the contact pressure over the clasping agent and reduces the transmission transfer. Hereby the disc servo-mechanism has two pressure cavities, which will be respectively provided with oil over a radial borehole in the locating disc and over an opening made along the disc movement and over two vertical radially running boreholes made on the hollow bored variator shaft. In addition, a duct is provided in the axial direction above a radial borehole in the variator shaft, which ensures the oil supply.
In line with DE 693 04 105 T2, which concerns a pulley used in a continuously adjustable transmission and with DE 699 08 828 T2, which concerns a control for a continuously adjustable transmission, two pressure chambers are also revealed for the hydraulic adjustment of the pulleys, which are respectively supplied with oil by two non-piercing radial boreholes made in the hollow bored variator shaft and a radial running duct in the locating disc.
A conic disc clasping transmission is further known from DE 100 37 136 A1 in which the pressurizing medium supply of the two intended pressure chambers for the locating disc adjustment is done by way of a fluid connection, which is built as a longitudinal borehole in the variator shaft as a radial running piercing duct in the variator shaft, as well as a radial running duct in the locating disc, whereby the two pressure chambers are connected to each other. Hereby a rotating groove is located in the locating disc for ensuring the oil flow regardless of the axial position of the locating disc. With this construction, an oil supply is possible even in a pressureless condition in case of an oil supply delay.
The present invention approaches the task based on a pressure conduction between the variator shaft and the pressure chamber for the axial displacement of the mobile disc (location disc) of a pair of conic pulleys of a continuously adjustable automatic transmission, in particular a clasping transmission which results in a simplification of the components manufacture. In addition, the need for an oriented assembly is eliminated.